Multistation photometric analyzer

ABSTRACT

A multistation, single-channel photometric solution analyzer having a rotor adapted to carry a plurality of removable cuvettes in the form of rigid, hollow, elongated bodies exteriorly engaged by a flange seating against an axially extending surface of the rotor. The cuvettes may be affixed to a flexible belt to facilitate transport, installation, and removal of cuvettes as a group.

United States Patent MULTISTATION PHOTOMETRIC ANALYZER 10 Claims, 4Drawing Figs.

U.S. Cl 356/197, 356/246, 250/218 Int. Cl G01n 21/24 Field of Search250/218;

PHOTO- PULSE ocrecron SCANNER PULSE I PEAK READOUT l 10 l 2 1 l2 4 J j 6-5 REVOLUTION I nerecron 'fml I TACHOMETER semen/non LIGHT SOURCE [56]References Cited UNITED STATES PATENTS 3,518,012 6/1970 Franklin et al356/197 Primary Examiner Ronald L. Wibert Assistant Examiner-Orville B.Chew, ll Altorney-Roland A. Anderson ABSTRACT: A multistation,single-channel photometric solu- I PATENIED JUN nan SHEET 2 OF 3 IINVENTOR. Norman- 6. Anderson BY 7 A &

ATTORNEY PATENTEBJUN nan 1 .SHEET 3 [IF 3 M R mm mm W A 1 6 ATTORNEY.

This invention was made in the course of, or under, a contract with theUnited States Atomic Energy Commission.

My invention relates generally to multistation, single-channelphotometric solution analyzers, and more particularly to improvements inrotor assemblies used therein, and to means facilitating thetransport,.installation, and removal of removable cuvettes as a group.

Copending Pat. applications Ser. No. 784,739, Ser. No. 827,l85, US. Pat.No. 3,547,547, of common assignee, described photometric solutionanalyzers wherein a rotor assembly is formed with a plurality ofsample-receiving cavities, or cuvettes, disposed in a circular arrayabout the axis of the assembly. Each cuvette is provided with axiallyaligned transparent windows. Rotation of the assembly successivelyinterposes the cuvettes between a light source and circuitry adaptedto'measure the phototransmittance of the various samples in the cuvettesand thus determine chemical species concentrations in the samples.

The analyzers described in the above-referenced patent applicationspermit a substantial reduction in the time required for the analysis oflarge numbers of samples. Those analyzers are, however, subject tocertain disadvantages. For example, the sample-analysis cavities, orcuvettes, must be cleaned very carefully between runs to' avoidcross-contamination of samples, corrosion of the cuvettes themselves,and darkening of the cuvette windows resulting from exposure to dyes,filmforming liquids, and the like. Also, such ar'ialyzersare not welladapted for certain analytical procedures -as, for example, where it isdesired to remove the samples rapidly from the cuvettes, transport thesamples to a heating zone or incubation zone, and then rapidly reloadthe samples in a photometric analyzer for reanalysis.

It is, therefore, a general object of this invention to provide aphotometric analyzer wherein successive samples are analyzed with littleor no cross-contamination of the samples, contaminationof the rotor, orrun-to-run deterioration of the light-transmitting properties of theanalyzer rotor.

It is another object of this invention to provide a modified photometricanalyzer rotor adapted for use with removable cuvettes.

It is still another object to provide an arrangement whereby amultiplicity of removable cuvettes can be transported as a group,installed in the above-mentioned modified rotor as a group, and removedfrom the modified rotor as a group.

Other objects of the invention will be apparent from examination of thefollowing description and the appended drawings.

SUMMARY OF THE INVENTION In accordance with my invention, thephotometric analyzer rotor is formed with a coaxial annulus formed witha circular arrayl of recesses extending radially outward from the innerperipheral surface thereof for the reception of removable cuvettes. Thetypical cuvette is a hollow, rigid, elongated body exteriorly engaged bya flange and having a closed, light-transmitting end portion. Mountingof a cuvette in one of the recesses brings said end portion intoregistry with axially aligned light-transmitting means carried by therotor. Rotation of the rotor successively interposes the cuvettes andtheir respectivelight-transmitting means between a light source and aphotodetector whose output is fed to circuitry for measuring the lightabsorbency of said end portions of the cuvettes.

To facilitate handling as a group, the cuvettes may be affixed to theface of a flexible belt, the center-to-center spacing of the affixedcuvettes corresponding to that of the recesses in the rotor annulus.

BRIEF DESCRIPTION OF TI-IE DRAWINGS FIG. 1 is a schematic diagram,partly in section, of a photometric solution analyzer designed inaccordance with this invention.

FIG. 2 is a series of four sectional views of a removable,double-function cuvette designed for use in a system of the kind shownin FIG. 1. The views illustrate the positions assumed by liquids in thecuvette during four successive stage of a normal operation of thesystem.

FIG. 3 is a perspective view, partly in section, of a belt-andcuvetteassembly designed for use in the system shown in FIG. 1.

FIG. 4 is a perspective view, partly in section, of an alternative formof the assembly shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, one form ofthis invention includes a rotor l, which is in the form of aflat-bottomed bowl having an axis of rotation. The bowl is formed withan axially extending sidewall 2, or annulus, coaxial therewith. Asshown, the base of the bowl is supportably mounted to a rotatable shaft3 which in turn is connected to any suitable drive means (not shown) forrotation of the rotor about said axis.

The inner peripheral surface 4 of the annulus 2 is bored andcounterbored to form a recess which extends radially outward toward theouter peripheral surface 6 of the annulus. The recess is proportioned toreceive an end of a cuvette 8. The cuvette is formed with 'an exterior,annular, medial flange 19 which seats snugly in the counterbore when thecuvette is in normal operating position, as shown. t

The cuvette 8 is a hollow and rigid body composed of trans parent ortranslucent material, such as glass or plastic (e.g., nylon, Teflon,polyethylene, polypropylene). The cuvette preferably is formed bystandard molding techniques. For example, the cuvette shown in FIG. 1can conveniently be fabricated by combining two molded and similarcup-shaped members, each having an exterior flange coplanar with itsopen end. These members can be cemented together, flangeto-flange, toform the cuvette 8. When the cuvette is in operating position, a closed,light-transmitting end portion 7 thereof is in registry with axiallyaligned light-transmitting means 10 carried by the annulus. The means 10may comprise axially aligned through-going openings (as shown in FIG.1), transparent windows, light-transmitting fibers, or the like.

Still referring to FIG. 1, the internal medial portion of cuvette 8 isprovided with a transversely extending barrier 11. The barrier isramp-shaped in cross section, the bass of the ramp being affixed to thecuvette.

The cuvette 8 is positioned in the annulus with its barriercontainingportion lowermost. Thus, the barrier extends both upwardly from thefloor of the cuvette and part way toward the opposite wall, presenting asloping surface to any liquid in the uninserted chamber 9 of the cuvetteand an essentially vertical face to any liquid in the inserted chamberthereof. At a selected speed of the rotor, centrifugal force will causeliquid to flow radially outward from chamber 9, over the barrier, butthe barrier prevents flow in the opposite direction whether the rotor isrotating or at rest.

As shown, the normally uppermost surface of cuvette chamber 9 isprovided with a port 12 at a point radially inward from the barrier l I.As will be described, this port is provided for the introduction ofsamples and reagents.

For simplicity, the rotor 1 has been described in terms of a singlecuvette mounted in a single recess in the annulus 2. The rotor will,however, normally be provided with many recesses of the kind described,each for the reception of a cuvette 8. Rotation of the rotor interposeseach of the cuvettes in turn between a photometric light source and aphotodetector, both of which are positioned to align with thelight-transmitting means 10 associated with each cuvette. The lightsource, the photodetector, and the output circuitry associated therewithfor measuring the light-absorbency of each cuvette are described indetail in aforementioned application Ser. No. 784,739 and will not bedescribed here as they do not constitute a part of this invention.

In a typical operation of the system of FIG. 1, the rotor 1 is loadedwith cuvettes 8, which are oriented as shown. With the rotor at rest, aliquid sample is introduced to the chambers 9 through the ports 12. Therotor then is rotated to a predetermined speed transferring the samplesto the end portions 7. One or more reagents then are admitted to thechambers 9 through ports 12, and the rotor operated at a speedtransferring them into the end portions 7, where they blend with thesample, providing an analytical mixture whose absorbance is thendetermined. 7

Referring to FIG. 2, the sequence of operations just described isillustrated in terms of a cuvette which is functionally similar to thatdescribed. In FIG. 2, the sample is designated as 13 and the reagent as14. The path of the light beam is indicated by an arrow. It will benoted that in the embodiment shown in FIG. 2 the cuvette chambers andthe barrier are formed as an integral unit. It will also be noted thatin cuvettes of the kind shown in FIGS. 1 and 2, the chamber 9 serves thefunction of the so-called transfer disc described in theabove-referenced patent applications.

It will be understood that my invention is not limited to the use of anyone type of cuvette, such as the two-chamber type shown in FIGS. 1 and2. As indicated in FIG. 3, for example, the cuvettes may be singlechambers 15 having flat upper and lower faces joined to an arcuate sidewall and having an open end coplanar with an external rectangularflange. As shown, a lower edge 16 of the flange extends inwardly andupwardly in the shape of a ramp to serve as the above-mentioned barrier.Alternatively, as indicated in FIG. 4, the barrier may be in the form ofan external tape 20 closing all but a small upper portion of the mouthof a single-chambered cuvette.

Again, cuvettes of the type illustrated in FIGS. 1 and 2 may be providedwith a succession of barriers l1 and, if desired, with a series ofcorresponding ports 12 for the introduction of liquids.

The above-described combination of removable cuvettes and an analyzerrotor adapted for using the same obviates to a large extent thecontamination, corrosion, and window-darkening problems sometimesencountered with rotors whose cuvettes are cavities molded, machined, orotherwise formed in the rotor body. Preferably, the removable cuvettesare formed of an inexpensive material permitting discard of the cuvettesafter several uses or even a single use.

To facilitate the transport, insertion, and removal of a multiplicity ofremovable cuvettes, I have devised a special beltand-cuvette assembly,three forms of which are shown in FIGS. 2, 3, and 4, respectively. Ineach of these arrangements, cuvettes are affixed to a face ofa flexiblebelt 17, each cuvette having a closed, light-transmitting end portion 7extending away from said face. As shown in FIGS. 3 and 4, the cuvettesare mounted in spaced relationship, their center-to-center spacing onthe belt corresponding to the spacing of the cuvette-receiving recesses(5, FIG. I) in the annulus (2, FIG. I). The cuvettes may-be removablyattached to the belt or, if desired, permanently secured thereto. Ineither case, the belt can be used (a) to transport, simultaneously, alarge number of properly oriented and spaced cuvettes, (b) to guide themounted cuvettes as a group into their respective recesses in the rotor,and (c) to remove the installed cuvettes as a group. Preferably, thebelt is not disengaged from the cuvettes following insertion of thelatter but is installed or removed along with the cuvettes.Consequently, in some embodiments the cuvettes and the belts are moldedas a continuous unit. If desired, the belt assembly is composed of aninexpensive plastic permitting discard of the assembly after a few usesor even a single use. As indicated in FIGS. 3 and 4 the belt may beperforated to provide ports for the introduction of liquids to theaffixed cuvettes.

Referring again to FIG. 2, the belt 17 is illustrated as mounted betweenthe confronting flanges of the mating halves of the cuvette 8. The beltmay, for example, be friction-fitted in slots formed at the interface ofthe flanges or may be cemented to the flanges. In the embodiment shownin FIG. 2 the flange nearer the end portion 6 seats against the innerperipheral face of the annulus 2 when the cuvette is mounted in therotor. In the arrangement of FIG. 3, the external flange of the cuvetteis secured to the belt 17 and seats against the inner surface of theannulus. In the arrangement of FIG. 4, the cuvette is formed with anintegral end flange. The body of the cuvette is passed through a hole inthe belt 17, with the flange seating against the belt. The belt seatsagainst the inner surface of the annulus 2 when the cuvette is installedin the rotor. The cuvette is exteriorly engaged by the belt, and thebelt may be described as a flange which seats against the annulus. Instill another embodiment (not shown) the cuvette is not formed with anintegral flange; instead, the mouth of the euvette is positioned flushagainst the belt and bonded thereto. Thus, the belt serves each cuvetteas a flange which seats against the annulus 2.

If desired the cuvette may be designed with its body portion forming anangle of less than with its flange. This permits the cuvette to bemounted with its end portion 7 lower than its mouth, eliminating theneed for a barrier to prevent outflow of liquid from the cuvette when atrest. If desired, removable cuvettes may be used in combination withtransfer discs of the kind referred to above.

The foregoing description is offered for illustrative purposes only, andit is intended that this invention be limited only by the scope of theappended claims.

What I claim is:

1. In a photometric solution analyzer including a rotor assembly forperiodically interposing at least one light-transmitting sample-analysiscuvette between a light source and means for measuring the lighttransmitted through the cuvette so interposed, the improvement whereina. said rotor comprises an annulus rotatable about an axis and having aninner and an outer peripheral surface, said annulus having at least onerecess communicating with said inner surface and extending radiallytoward said outer surface, said annulus carrying light-transmittingmeans adjacent said recess for passing light through said annulus andsaid recess, and

b. said cuvette comprises a hollow, elongated, rigid body having aclosed end portion of light-transmitting material insertable in saidrecess for registry with said light-transmitting means, and flange meansaffixed to said cuvette at a location remote from said closed endportion for seating against said inner surface of said annulus tomaintain said end portion in registry with said light-transmittingmeans.

2. The combination of claim 1 wherein said light-transmitting meanscomprises a pair of aligned apertures disposed on either side of saidrecess and extending from said recess to the exterior of said annulus.

3. The combination of claim 1 wherein said flange means is integral withsaid cuvette.

4. The combination of claim 1 wherein said cuvette is exteriorly affixedto a flexible flat member extending in a plane substantially normal tothe major axis of said cuvette.

5. The combination of claim 1 wherein said cuvette is composed of glass.

6. The combination of claim 1 wherein said cuvette is composed of aplastic.

7. The combination of claim 1 wherein said cuvette contains a solidbarrier which is sealably joined to the inner surface thereof and whichdivides the interior of the cuvette into adjoining chambers whichcommunicate through an open region above said barrier, said barrierpresenting a substantially flat and upright surface to said closed endportion and a sloping surface to the opposite end of said cuvette.

8. In combination with a photometric solution analyzer comprising anannulus rotatable about an axis and formed with circumferentially spacedrecesses extending radially outward from an inner peripheral surfacethereof, with each of said recesses adapted to receive a closed,light-transmitting end portion of a cuvette readily insertable in andremovable from said annulus, means for effecting the insertion andremoval of said cuvettes from said recesses comprising belt meansdisposable within said annulus in a contiguous relation with theinnersurface thereof and having a plurality of cuvettes affixed to aface thereof at spaced-apart locations along the length thereof, jeachaffixed cuvette having a closed, lighttransmitting end portion extendingaway from said face, the

9. The combination of claim 8 wherein said belt means and said cuvettesare of unitary construction.

10. The combination of claim 8 wherein said belt means is adapted toseat against the inner peripheral surface of said ancemeptmcemer spacingof Said affixed cuvettes correspond 5 nulus when said affixed cuvettesaremounted in said recesses.

ing to that of said recesses.

2. The combination of claim 1 wherein said light-transmitting meanscomprises a pair of aligned apertures disposed on either side of saidrecess and extending from said recess to the exteriOr of said annulus.3. The combination of claim 1 wherein said flange means is integral withsaid cuvette.
 4. The combination of claim 1 wherein said cuvette isexteriorly affixed to a flexible flat member extending in a planesubstantially normal to the major axis of said cuvette.
 5. Thecombination of claim 1 wherein said cuvette is composed of glass.
 6. Thecombination of claim 1 wherein said cuvette is composed of a plastic. 7.The combination of claim 1 wherein said cuvette contains a solid barrierwhich is sealably joined to the inner surface thereof and which dividesthe interior of the cuvette into adjoining chambers which communicatethrough an open region above said barrier, said barrier presenting asubstantially flat and upright surface to said closed end portion and asloping surface to the opposite end of said cuvette.
 8. In combinationwith a photometric solution analyzer comprising an annulus rotatableabout an axis and formed with circumferentially spaced recessesextending radially outward from an inner peripheral surface thereof,with each of said recesses adapted to receive a closed,light-transmitting end portion of a cuvette readily insertable in andremovable from said annulus, means for effecting the insertion andremoval of said cuvettes from said recesses comprising belt meansdisposable within said annulus in a contiguous relation with the innersurface thereof and having a plurality of cuvettes affixed to a facethereof at spaced-apart locations along the length thereof, each affixedcuvette having a closed, light-transmitting end portion extending awayfrom said face, the center-to-center spacing of said affixed cuvettescorresponding to that of said recesses.
 9. The combination of claim 8wherein said belt means and said cuvettes are of unitary construction.10. The combination of claim 8 wherein said belt means is adapted toseat against the inner peripheral surface of said annulus when saidaffixed cuvettes are mounted in said recesses.